Inserted-tooth milling-cutter.



No. 650,924. Patented June .5, I900. J. W. BOYNTON.

INSEBTED TOOTH MILLINGQCUTTEB.

(Application filed June 23, 1899.)

(No Model.)

JOHN W. BOYNTON, OF NEl/V BEDFORD PATENT OFFICE.

, MASSACHUSETTS, ASSIGNOR TO THE MORSE TWIST DRILL AND MACHINE COMPANY,OF SAME PLACE.

lNSERTED-TOOTH SPECIFICATION forming part of Letters MILLING-CUTTER.

Patent 1\T0. 650,924, dated June 5, 1900.

Application filed June 23, 1899. Serial No. 721,558. (No model.)

To all whom it may concern-.-

Be it known that I, JOHN W. BOYNTON, a citizen of the United States,residing at New Bedford, in the county of Bristol and State ofMassachusetts,have invented certain new and useful Improvements inInserted-Tooth Milling-Cutters, of which the following is aspecification. s

In manufacturing milling-cutters of large diameter it has heretoforebeen the custom to make them with a cast-iron or soft-steel hubappropriately grooved to receive the cuttingteeth, which are formed oftool-steel and inserted in said grooves. It has furthermore been thecustom in many cases to insert these teeth at an angle to the axis ofthe cutter in order that the cutter may make a shearing cut when inoperation. In such cases it has been the invariable custom, so far as Iam aware, to give the inserted tooth a plane cutting-face, or, in otherwords, a face which has no curvature in any direction. The result ofthis construction is that by reason of the aforesaid angle between thetooth and the axis of the hub the angle between the cut ting-face of thetooth and the cylindrical surface of the hub varies continuously fromone end of the tooth to the other, so that the said cutting-face of thetooth can lie at one point only in its theoretically correct position,which is such that the cutting-face is everywhere normal to the adjacentcylindrical surface of the hub or, in the case of a hookingtooth, at aconstant acute angle thereto. It has also heretofore been proposed toform an inserted-tooth milling-cutter by suitably disposing a series ofspirally-formed cuttingteeth around a suitable central sleeve or spindleand uniting said parts by casting a softmetal body between and aroundthem.

It has been found that the first above-described class of cutters, inwhich a solid grooved'hub is employed, possesses advantages over thecomposite cast structure later referred to, and my present improvementrelates to insertedetooth cutters the hubs of which are formed andgrooved prior to-the insertion of the teeth.

In the accompanying drawings, Figure 1 is a perspective Viewillustrating a cutterformed in accordance with myinvention. Figs. 2 and3 are end views of similar cutters, further illustrating my improvement.Figs. 4 and 5 are respectively a side elevation and a crosssection of atooth before it has been turned and milled, as hereinafter described.

My improved method of producing an inserted-tooth cutter consists infirst forming the tooth with a plane face, then inserting the same inposition in a hub properly grooved to receive it, turning its outer flatface to correspond with the cylindrical hub, and, finally, milling orotherwise working the cutting-face of the tooth, while in position inthe hub, into a spiral surface normal at all points to the surface ofthe hub or at a constant acute angle thereto.

As it is often desirable to make these outters of considerable lengthfor use on heavy work, the amount of departure from the proper locationin such case becomes considerable, and by means of my improvement,whereby this is corrected, I produce a much better and more efficienttool than was produced under the old methods.

In the drawings the hub 2 is shown as cast or otherwise provided with asuitable number of grooves 3, each adapted to receive and retain aninserted tooth 4. In Fig. 2 is shown a tooth 5 as it appears when firstinserted in the hub 2thatis to say, with its cutting-face 6 flat andlying wholly in one plane. After the teeth have been inserted in theform shown at 5 in Fig. '2 their outer edges are turned and then madeconcentric at all points with the cylindrical hub and the faces 6 aremilled down to the dotted line 7, which indicates the cuttingface of thetooth as it is when finished, when, as will be observed, it iseverywhere normal to the surface of the cylindrical hub 2, so that thesaid cutting-face if prolonged toward the center of the hub would form aspiral surface composed of radial lines or lines passing through theaxis of the cylinder.

In casea hooking-tooth is desired the teeth 5 may be so milled thattheir cutting-faces 8, Fig. 3, will ultimately lie at every point in aplane tangent to a small cylinder 9 concentric with the axis of thecutter, as shown in Fig. 3. The cutting-face 8 will thereby be made tolie at an acute angle with the surface of the hub 2, but such angle willbe constant throughout the length of the cutting-face.

It will be understood that in place of inserting the plane-faced teeth 5in their final position in the hub 53 before milling theircutting-faces, they may be inserted in a blank or pattern correspondingin its dimensions and in the arrangement of its grooves to the hub 2 andmilled therein and afterward removed therefrom and inserted in theirfinal position in the hub 2.

It will be seen that in constructing a cutter in accordance withmyinvention the grooves in the hub for receiving the cutting-teeth haveperfectly plane sides, and hence are easily formed or cut as comparedwith the spiral grooves, which must be cut to receive pre-

